Process for producing ammonium sulphate



Jan. 8, 1935. F. w. SPERR, JR 1,986,899

I PROCESS FOR PRODUCING AMMONIUM SULFHATE Filed Jan. 18, 1929 '2 Sheets-Sheet .2

area/)2 I e BY ATTjRNETi.

' a w-PRooEssroa PRonUoiNG-AMMoNIUMi Patented Jan. 8, f r v I Frederi ck Jr; Pittsburgh, assignbrc p i T I tojThe'Koppers Company of Delaware, a corpo ApplicationlJanuary 1 8, 1929,.SerialNo.

" o1 m .-(o1;23 119) t I and; in finelycomminutedform,passesupwardly through the solution. GasesJand vapors collect- Thisinvention.relatesto-a process and appa ratus for oxidizing ammonium sulphite' to':produce ammoniumsulphate, and more particularly to; the manufacture of ammonium sulphate. from ammonia liquorsfandwaste gases containing sul-'- It has been fOund that'fin the treatment of ammoniacal solutions; or more particularly ammoniumsulphite solutions; with 1 gases to produce ammoniumsulphate, greater yieldsof the latter are obtained from solutions of certain concen trations and when the gases in finely c'o'mminuted state are comrningledwith the solutions; It has alsobeenfound that' the yields are dependent somewhat on the rateat which thegase's are passed through thesomuons;

I Solutions of ammoniumsulphite' of various Q concentrations ofup"to20% or-more may be used in this process, but it has been found "that the best results are obtained with'solutions containingfrom about %--to about %ammo-nium sul phite. The ratesiagtfii liich the oxidizing gases are passed into the solution are given by :way; (if

example and not by way of'limitation. A -range of rates which appear to give good rsults, is from about cubic feet per hour per'gallon to about 300 cubic feet, per hour per gallonij Ariintervmediate rate of about 140 cubic reeeper hour'pe'r gallon appears to fgivei very; favorable results. l It will be appreciated thatf'the inost desirable rate will' vary with thetype arid-f size oi apparatus f V Various types of apparatus maybe used in-cone nection with the processfoifthis invention. Ex amples of suitable apparatus are "shown the accompanying drawings in Which Fig. 1 is a 'view partly in vertical sectionand partly inelevationofjone form of apparatus;

Fig 2 isasi paratusfand A Figs. 3 and 4 are similar pviews of "further modifications.

In Fig. 1 an arrangement"is shownin; which-- there is a closed tank 1 ',"provided wi th a gas com-.

,minuting device such? as earthenware or filtrose, extending horizontally across the interiorof the tank and placed ashort distance above the bottom thereoffto permit the v entrance of the oxidizing gas through theflpipe '5 into the tank 1 below theplate 2: Ifhe solution to be treated, as for instanceammonium ,sul-

. phite solution, isplacedinthetank 1 above the porous plate 2, inlet means'13 and'outlet means! forthe solution being provided in"the side of the I The oxidizing as asse-ithmu n the 1ate'2 ilar view or another form an;

a tions pla o i f ing above thesurface of the solutionare led into a saturatorfi containing sulphuric acid of proper r Alternatively, apparatus such as that shown in Figs. 2 and3 may be used the process jof this, invention.

in connection with ""In Fig. 2a tall tower 7; 20: to in height and of relatively; small, diameter, is providedv at: the top with inlet means i 8 for the; ammonium sul-O phite solution fandat the ,bottom with .outlet means 9:;for the ammonium sulphateusolutioni The oxidizing'gas passes into the solution at the. bottom of,.the-tower through a. perforated pipe 10,.preferably ringfshap'ed. The waste gases are passed OlltglQf the top of 'thetowerthrough: the pipe11..-

"v- In the' operationof-the apparatus shown 'in- "Fig- 2, the ammonium sulphite solution, is led from-tank 12 throughp'ipe 8 and into the top of I the= tower- 7W The tower is. kept almost full and the; solution is permitted to fiow out through pipe 9 ata rate such as to ensure the oxidation of the bulk 1 of; the ammonium sulphite. The airi. is. forced into the 1 solution through. the perforated pipe l0, prleferably at a pressuregreat'enough to overcome the resistance encounteredby the ,air

in the column of liquid above the perforated pipe 10. In'this apparatus a counterflow processwis used which is peculiarlyefficient'in that there is littleor 10 8 of ammonia and less airis necessary to flbring about complete oxidation. The ammonium sulphate 7 solution coming -fromthe bottom of the towerthrough pipe 9 may betreated inany desirable manner to obtain the ammonium sulphate. -f 1 H .J e As shown in Fig; 3,2, combination oftowers; preferably two" similar to thatshown in Fig. 2,- may be'employed. Towers-13andf14=are placed preferably one above the other and connected by' apipe 15, sothat the ammonium sulphite solution passingkfromthe supply tank 16 through pipe l'l into the" top of the upper tower 13, passes ,downwardly through the pipe 15, into thetop of the lowertower 14, and the ammonium-Sula.

' come the resistance encountered by the air in duxtosuchheating... A

the column of liquid above the perforated pipe 19, and that in the column'ofliquid aboveithe I collected'in'the usual manner.

perforated pipe 21.

The rate at which the air is led into the solution is so controlled as to: produce satisfactoryresults. The rate depends on and the concentration of andron therate of flow-of the solution down throughthe'towersp r x r r Theapparatus shown in l igpiijis: arranged to provide ior-:the heating of -ammonium sulphite solutionandjalso to prevent any loss ofammonia steam coil may be placed in.,the.;solution'inythe lower tower near the botv In Fig.4 an: apparatusfis showndesired temperature upjto boiling.

tom-.andipreierablyput of'the'path of the -oxidiz-, ingefgas passing,;upwardly-;through the liquid. The, liquidirin tower 14 may be heated to any The solu tioni-in theupper tower13-is kept at normaltemperature and maybe cooledgif. desired, by the use of a cooling coil.

: The process of thiszrformrof my invention is particularly adapted to the production. of ammonium sulphate fromiammonia liquors,- and waste-gases: containing: sulphur: dioxide. Y. In this caise,;.the-.wasteigases containing sulphur. dioxide are: led" intosthefiammoniazliquors to produce ammonium sulphite. .:The ammonium. s ulphite' 3 is :oxidizeduto? ammonium sulphate by passing a containing free, ioxyge'n' finely: commmuted gas into thesisolution of ammonium 'sulphitewandi comminglingthegas therewith. The gas is then led: intoa: saturator containing sulphuric acid of about 66 B. to convert any entrained ammonia into ammonium sulphate. qThe. ammonium sulphate produced is separated .from the solution by eva'poration of the liquid and-the well known I processesof crystallization andrfiltration or.- cen' phategf rom ammonium sulphite with; anoxidiztrifngingu I.

Alternatively, the .sulphur. dioxide I is mixed with-airrand the mixture led intothe ammonia liquors wthereby ioxidizing-gzthe ammonium 38111- phiteuas-soon as formed in, the reactionjof the sulphur dioxideiwith thevammonia. in which a batch'rtreatment may-be employed and the gas recirculated :through the solution; to be treated.

' Thiswtype of apparatus is particularly adapted to the treatment-of ammonia liquors simultaneously with fain.and' sulphurldioxide to.;-carry out the reaction-from: ammonia to ammonium sulphite and then-to ammonium sulphate; in one operation. The ammonia liquors are placed in a tank a i 23; similar in construction to thetank 1 shown in Fig. 1. A mechanical agitator may be sub-- stitute dforthe porous plate 25. A tank 24 isfilled with am ixture of gases containing oxygen and sulphur; dioxide. A small excess or sulphur dioxide and;a larger excess of oxygenare preferable. For example, about four times-the amount ofairinecessary to complete the reaction may be -use d. I i

Waste gases are passed out of the top of the tower 13 through pipe 22. The air is passed into pipe 19 at a pressure great 'enough to; overthe temperature the solution treated,

monium salts, in the form of carbonates, sulphides, etc., and various tarry and oily substances, ammonia ispreferably distilled off and The ammonia solution thus obtained is'then treated in accord- "ance withthe-processof this invention to produce ammonium sulphate.

Apparatus such as that shown in Figs. 2 and 3 are particularly efficient in connection with the process of this invention. Owing to the pressures existingin the towers described, the gases need not be as finely comminuted as when introduced into an apparatus such as that shown in Fig. 1 wherein the body of liquid treated is relativelyshallow; Furthermore, the aforesaid towers ensure better contact of liquid and gasthan towers into which the liquid.- isgsprayed orin which the gas merely passes over the surface of the liquid-or in which the gas is passed through shallow bodies of-liquids- H The apparatus and-processor thisinvention give highly improved results Under proper conditions almost complete oxidation of ammonium sulphite can be accomplished.

. Iclaim. as my inventionz. v .1. A process comprisingintroducing oxidizing. gas under pressure into the lower portion .of a tall narrow column of about '20; to 60 feet in height of liquid containing ammonium sulphite and thereby'efiecting the oxidation 2of ammonium sulphite .to ammonium -sul-phate with oxidizing 2. A process- -con 1prising introducing finely comminuted r oxidizin ,gas i-ntd a deep -column of about 20 to 60'feet height of ammonium sulphite solution and thereby effecting theoxida t' on of.ammonium.- sulphite to ammonium sulphate-with oxidizing'g'as y I r 3. In: a process .ofproducing. ammonium suling'gasathestep oi finely comminuting the oxidizinggaswi-thina deep column-of about 20 to 60 feet in heightzbf a.- s o lution of-ammonium ulphite; A". I I. i I

4. --a process or oxidizing ammonium -sulphite to-ammonium sulphate by means of an oxyg en-containing gas, the improvement. which comprisesmaintaininga deep column of about 20 to 60 feet in height of ammonium sulphite solution, and introducing the oxygen-containing gas-to the lower portion of" saidcolumn by passing saidgas through a porousseptum in contact with said solution;

FREDERI arme from 'gasgliquor, containing free ammonia, am- 

